1. Field of the Invention
The present invention relates to a wireless communication device and method of adjusting antenna matching in particular capable of automatically adjusting antenna matching such that an isolation between dual antennas is optimized at any moment.
2. Description of the Prior Art
Wireless communication devices, such as mobile phones, tablet computers and laptop computers, receive and transmit wireless signals by an antenna for exchanging radio waves to access the Internet. Different wireless communication systems are developed as the wireless technology advances, and a number of antennas with which the wireless communication device is equipped may be increased in order to adapt to the different wireless communication systems. Antenna configurations corresponding to the wireless communication system supported by the wireless communication devices are listed in the following Table 1:
TABLE 1Antenna ConfigurationWireless Communication SystemOne main antenna2G: GSM (GPRS, EDGE)One main antenna and3G: UMTS (WCDMA, HSPA),One auxiliary antennaCDMA2000 (1xRTT, EV-DO)Two main antennas4G: LTE
In detail, the second generation mobile communication system, hereafter called 2G system, including Global System for Mobile communication (GSM) is a single-input single-output (SISO) system configured with only one antenna, and the wireless communication device is equipped with single antenna for receiving and transmitting. The third generation mobile communication system, hereafter called 3G system, including Universal Mobile Telecommunication System (UMTS) and supporting Code Division Multiple Access (CDMA) technique is a single-input multi-output (SIMO) system configured with dual antennas, and the wireless communication device is equipped with a main antenna for receiving and transmitting and an auxiliary antenna for receiving only. The fourth generation mobile communication system, hereafter called 4G system, including Long Term Evolution (LTE) system is a multi-input multi-output (MIMO) system configured with dual antennas, and the wireless communication device is equipped with two main antennas for receiving and transmitting, which is also known as antenna diversity.
Moreover, different telecommunication operators may utilize different wireless communication techniques, even though the wireless communication techniques are the same, operating frequencies may be different in different areas. Thus, a demand for a wireless communication device capable of supporting multiple wireless communication techniques and operating frequencies appears, which allows the wireless communication device communicating with base stations in different areas and supporting different wireless communication techniques.
Nowadays, most of the wireless communication devices are configured with dual antennas in advance for supporting the MIMO, SIMO and SISO systems and multiple operating frequencies. However, an isolation between two or more antennas shall be considered carefully if they are operating in the same frequencies. If the isolation between the dual antennas is bad, transmitting and receiving efficiencies of the dual antennas is effectively weakened.
With dual antennas configuration, the diversity antenna (i.e. the another main antenna) is used for receiving only when the wireless communication device is switched from the MIMO system to the SIMO system, and if the isolation between the main and diversity antennas in a transmitting band is bad, a transmitting efficiency of the main antenna in the transmitting band is effectively weakened. On the other hand, only the main antenna is required when the wireless communication device is switched from the MIMO or SIMO systems to the SISO system, and if the isolation between the main and diversity or auxiliary antennas is bad, transmitting and receiving efficiencies of the main antenna is effectively weakened.
Therefore, how to adjust and optimize the isolation between dual antennas whenever the wireless communication device is switching the wireless communication system from one to another is a topic in the industry.